Range finding, horizontal angle measuring, and angle of site instrument



July 28, 1936. J. T. ZAK 2,048,722

RANGE FINDING, HORIZONTAL ANGLE MEASURING, AND ANGLE OF SITE INSTRUMENT Filed Dec. 11, 1934 TR REFERNC w OBJECT.

Patented July 28, 1936 UNITED STATE RANGE FINDING, HORIZONTAL ANGLE MEASURING, AND STRUMENT ANGLE OF SITE IN-' Joseph T. Zak, Fort Benning, Ga.

Application December 11, 1934, Serial No. 756,992

7 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3'70 0. G. 757) This invention described herein may be manufactured and used by or for the Government for governmental purposes, without the pa ent to me of any royalty thereon.

This invention relates to a range finding, horizontal angle measuring and angle of site instrument, and the primary object thereof is to provide an instrument of this character which is adapted to be easily and quickly operated to any position for determining the range, horizontal angle and angle of site to meet the conditions of direct and indirect laying (overhead fire) with a machine gun or the like. 7

Another object of my invention is to provide a range finding, horizontal angle measuring and angle of site instrument which is simple in construction, efficient in use, light in weight, and which is not liable to get out of order.

With the above and other objects and advantages in view, the invention specifically consists in features of construction, arrangement and operation of parts which will hereinafter appear. For purposes of illustration, the invention will be described and claimed with reference to the accompanying drawing in which like numbers distinguish like parts and in which- Fig. 1 is a perspective view of my invention;

Fig. 2 is a horizontal sectional view taken through the slot and slide of one of the arms.

Fig. 3 is a diagrammatic view illustrating the manner of solving a range problem with themstrument;

In carrying out my invention with the form of instrument illustrated in Figs. 1 to 3 inclusive of the drawing, a trio of arm members A, B and 0, made of any suitable material such as aluminum or wood are provided which are pivotab-ly connected together at one end by any suitable, means such as a bolt, washer and nut construction I. By pivotably connecting the arm members A, B and C together the instrument may be easily and quickly adjusted to an operative position, or be folded when not in use to reduce the size thereof. In order to hold individually the arm members A and B in adjusted angular position on the arm member C, suitable means such as the bolt, washer and nut construction I, are provided on each of the arm members A and B. a V

The arm member A is provided with a range corrector scale 2 which provides a range corrector for varying angles of a target observer reference object, i. e., in per cent of correction required, and a mil scale 3 illustrated by the symbol consisting of a double-headed arrow with a wavy central portion because ofthe small scale of the drawing. The scale 3 is inscribed along the. entire forward upper edge of the arm member and is superimposed on the range corrector scale 2 where the two scales 2 and 3 work jointly. A sight comprising a mirror 4 containing a horizontal 5 reference line 5 is provided on the lower side edge of the arm member A adjacent the pivoted end thereof. Fromthe line 5 as zero, a plusmil scale 6 is inscribed on one side thereof along the edge of the arm member and a minus, mil scale 10 6' is inscribed on the other side thereof. The arm members A and B are each provided with a bolt receiving slot I which extendsacros's the entire width of the arm members and longitudinally thereof. Slidably mounted on the forward side of each of the arm members A and B are sighting slides 8 and 8' respectively having centrally located bolts II and studs 9 provided there on, which are adapted to work in the slots 1, while the upper surface of they sighting slides 8 and 8' are provided with aiming marks l0 and i0 and 22 and 22' respectively. The studs..9 are provided to prevent rotation of the slides 8 and 8' on the arm members A and B. The bolts Ii on the slide 8 and 8' project through the 5 respective slots 1 and are provided with nuts l2, coil springs I3, and washers I4 on the free end thereof for adjustably setting the sighting-slides 8 and 8' along the arm members A and B. In order to freely move the sighting slides 8 and 8 along the arm members A and B, the nuts l2, which in the present illustration are shown as wing nuts, are unscrewed until there is but a slight tension of the spring I 3 between the washers l4, and when it is desired to clamp the sighting slides 8 and 8' in adjusted position on the arm members the wing nuts I! are tightened. The arm member A is further provided with a weight l5 and a pin receiving aperture I 6. The weight I5 is attached to the outer end of the arm member and provides means for holding the instrument in proper operative position while the aperture i6 is adapted to receive a pin I] provided on the arm member 0 when the instrument is ing used for determining the angle of site of a given object. I I V The arm member B is provided with a range scale [8 which in the present instance is marked to read ranges from 400 to 1600 yards and 8. mil scale l9 both of which are inscribed on the for-y ward upper edge thereof. The mil scale l9, which is illustrated by the symbol consisting of adoubleheaded arrow with a wavy central portion because of the small scale of the drawing is superimposed uponthe range scale I 8 where the range scale I8 7 and the mil scale I9'work jointly. V

The range scale l8 of arm member'B is based on the followingcformulap'RM equals 1000 W 5 owhere R is the range, M the angular width in mils oi the t'argetgor base line, and Wthe lineal width of thftarget or base line'ij- Inthe present 'case the range scale I8 is calculated fora base.

l r 7 line of fifty yards Where thebase line and refer-- 1 61106019180? are at right ,angles to'the observer target line and the range scaleior the instrument is held at a computed constant distance fromthe eye of the user of the instrument.j Inasmuchas the direction of the baseline will vary with the V 15 position of .the reference objec't- (-the'object which j determines the direction of base llnelthe actual W of the formula will become less as the angle target-observer-reference object becomes-less 'andi l c the actual range reading will be correspondingly 12 greater tha cthe.corre t an el eadin t mass '1) i e; obt in ng. raised t et -l raneei a 2. 91 119 3 v the plus and, nmusj angle, of

' sit? scaleon a m rriembe i A' for computing' 'the quadrant elev s. Inscribed on" the pivoted end of the arm memberjC are lines 29 which (are nrql fi at on; iha ni 1 ed f t a m members A and B henjthese arm v membersare ,in'oper n rposition'pn th arm'membe'r c. The

lines 28 are;firovided assuring uniformity iriithtr ,pect.t fg eeh e jia w h t e a member v A .mathematihal equation 130 may a o e ins rib dpn. the a mym m TC' otprQ:

t mi i 111d t me drawingtfor the determination of range s" i an d horizontal angle 50 m a urina s a l ws r ah s min t arm m mbe A; .B nidIQ o th i st u e t ha e b n i lm flql ed eng neers memb A n .B- v ee 'adiu' te r Q it e nnimem rqli o ation of the' lines ZSjand clamped in place'by the 55 b0 afidnu fcor'istr'uctioni prov ded o n each of the ;arm membrs3A andB thiristrument is ready :rofr use; iii-determining ranges and 'hori- Zofital angle 'measuringi' Referring' 'toFig'i 3of the':'-drawing,. 'a' and "a' and 'b' and 7h designate 7 60' points :or positionslon the armmen'ibers'A'and'B of: the instrument including-the range scale 4:8

7 'on :the :arm' member =B;and the range correction scale2-of thearm member A; The observer sta ti oried at flslides jthe sighting-slide llf on; the arm emes. l n la-the-za m n rme e he left side thereof rests opposite thein finityrmark -23. Thetobserver thenzclamps the sighting; slide to the arm memberzandplacesthe :mouthpiece '26 of 'e r tm 'mberlC I his ii fi l w h h s teeth 6 a g ainst the teem stops 21.? :rrne observer, hold- {places the:airningFmarK-I [On the le s e [o .v the'sighting slidevil' under the ta'rget, He 'next 75 slectf'sl'at convenient and distantreference object 7 2 04 7 2 7 7 3. R LE1. 7'

ferent positions for range 'readin of co resp ..i.ng targets andthen slides thesightin slid arm memberAfI c such as a tree which intercepts the arm'member I A and with the right hand slides the sighting slide 8 on arm member A so that the aiming mark ID on the right hand side thereof intercepts the V:

reference object. The observer now has'the left 5 aimingmark 219i the slide 8hon armqnemberjB von thetarget and the aiming mark [0 on the right side'of the sighting slide 8 01; arm member A-on the reference object in which case he clamps the sighting slide 8 to the arm member A by 10' means of its nut 1 2: If the observer desires to take the ranges .to other objects intercepting the arm member B with the use of the same base line,

a he takes arpencil note of the position of the aim- 7 ing mark on sighting slide 8 for each target. He can do this since the arm 'member A is marked off in the mil rule in units so small as to permit accurate'plotti'ng of 'positionof aiming mark.

The observer now moves the selected length of theibase line, in the direction ofthe reference object. and at the point 0' {(the other ehdjof the base line) jas indicated in 3 ofjthe dr he takes a second observation by; end of the.instrument,;i. egjright'i'ai v ill on slide 8, which is clamped tthe position determined by n Or' Ia pedi gees i e y, fi' f of arm member B1130 the leftl'untiljthe'jaimihg mark 22 thereofintercepts theftarget. hebe- 1 server then takes the instrumentout of his mouth andnotes that the range asif orfexamp 0250, yards is indicated exactlyby the nositionfoffthe aiming. mark 22' oppositethe, inscribed range scale 18. The observer a1so-notestha tion of a or a in Fig.3 or the position, the reference object on the "arm -,member A ;i di ted th a m n li-i l 0 th? ri hts-U sighting 'sliderfl. The; range Corrector scale 2 n h m: mem e A adja nt e slide 1 .1 11 40 7 'd ca i th amoun r 'p t q e u ted t have 'a true reading. of the range,"as forexample, the ume a iiih o e Co c or" ca e 2 indicates'that themperator mustfsub act percent from the range readingofzfi have the correct re'adingxu "1,1 I t Qood'res ults mayfbe obtainedwithoritthelme c o f'sighting slides 8 and 8/ by means of malring reading. and observation directly from-'rarigefscale' andrange corrector scale. 'In' thiscase initial adjustment is madejby placing infinity mark on the targetand a given percent line ,or'r'narkion the percent ,corrector scale adjacentithel e lected referenceobjectwhich is brought'tofcoin 'clde' With'that object by m eans ofloo'sening' the nut and gb olt construction I, to which the' 'arni members A, J13 and-Q,; are pivotall'y coh necte'd' 'arid swinging arm member A uritil such; coincidence is accomplished-andratll as illustrated in" Fig.f

of the drawingftl' e observer places? the reference 35 v object'in'line withthe previousl'y sielected percent corrector marlqat the; same time'glancing'toward therange's'cale to see'wherefthetar'get intercepts the} range sca1e,;which isthejrangePas res to be corrected by theIsubtractiOn' of-Ethe indicated percent of correction td "on the e For the hsake of. accuracy'and convenience the normal base line of fifty" yam -ma be varied in practice; A 25-yard base lineha's givenan 'av- 7Q ferag'e of about '-2 errorfor ranges up to' 500 ard 'but when using me ee-ya d bafs'e 'lihethe- 1 final range reading"must be-balanced. For results of precision at" distant rangesa 50-yard bas'e line can 'be" used 'le'aving {the finahrange 're'adirig as i t the posi- 35' read. Inextremely long ranges the base line can lac doubled for accuracy, hence the final range reading-must be doubled to secure correct range. It is possible'to accurately take the range to target several thousand yards distant provided the base line is correspondingly increased.

jlffhen a suitable reference object cannot be located to the right of the target, one can be selected to the left thereof and the, procedure in determining range will be the same except that the infinity mark will be placed on the reference object and the target will coincide with some point on the range corrector scale. The mil scales .3 and Won the arm members A and B respectively, afiord a means of measuring horizontal angles. The sighting slides Band 8' on the arm members A and B respectively with the aiming marks It, I and 20, 20' provided thereon,

arev similarly used in determining the left and right sides of anangle measured in mils.

In determining angles of site of a given object the arm members A and B are removed from the arm member C, and the arm member A is pivoted on arm member C by means of a hole It provided thereon, in which the pin I! on ar'm member C is adapted to be inserted, with the mirror 4 facing the-end 26 of arm member C and the horizontal reference line 5 lying in the same plane as the axis of the pivoted connection of the arm members A and C. This angle of site measuring feature of the instrument together with the means for the computation of quadrant elevations, is the same in principle as disclosed in my prior Patent No. 1,723,456, with the exception that the image of the pupil of the aiming eye is bisected by the horizontal reference line 5, in the mirror 4 when determining and maintaining the horizontal level of the instrument, since there is no peep site or rear site for the instrument in this case, the image of the pupil of the aiming eye must be bisected by the horizontal reference line 5 of the mirror 4, on arm member A, for leveling the instrument. In order to make the mil rule and angle of site scales uniformly applicable to all observers using the same instrument without the use of an individual corrector, the instrument should be held so that the end of the arm member C containing the mouthpiece 26 is held against the cheek just under the aiming eye. If individual corrections are known the instrument can be held in the mouth with the teeth against the teeth stops 2'! as for finding the range, thus giving greater steadiness tothe instrument.

The above disclosed instruments can be used in a sitting, kneeling, standing or prone position. It has been found in using the instruments that the position for obtaining the greatest steadiness thereof is in the sitting position with the elbows resting on the knees and the breath held as in firing a rifle. When using the instrument in the prone position the observer lies on his back, feet toward the target and head raised above the breast. For measuring the base line a five or ten yard length of any suitable Wire, such as picture wire, may be used. A good string gives satisfactory results. Careful pacing of base line eliminates the need of a string.

Having described my invention, what I claim as new and wish to secure by Letters Patent is:

l. A range finding, horizontal angle measuring and angle of site instrument comprising a trio of arm members pivotally connected together, one of said arm members providing means for holding the other of said arm members a predetermined distance fromQthe free endthereof and means provided' on said first mentioned arm member defining the angular operative position of said last'mentioned arm members with respect to each other and with said first mentioned arm member.

2. A range finding, horizontal angle measuring and angle of site instrument comprising a trio of separable arm members pivotallyconnected together,- one of said arm members providing means for" holding the other of said arm members a predetermined distance from the free end thereof and a sighting member having aiming marks slidably mounted on each of the last mentioned arm members.

3. A range finding, horizontal angle measuring and angle of site instrument comprising a plurality of arm members pivotally connected together at one end, the free end of one of said arm members adapted to be held in the mouth of the observer for holding the other of thesaid arm members a predetermined distance with .respect to his eye, a sighting slide having aiming marks slidably mounted on each of said last mentioned arm members and means for holding said slides in adjusted position on said arm members.

4. A range finding, horizontal angle measuring and angle of site instrument comprising a trio of separable arm members pivotally connected together at one end, the free end of one of said arm members adapted to be held in the mouth of the observer for holding the other of said arm members a predetermined distance with respect to his eye, a slot and an adjustable sighting device containing aiming marks provided on each of said last mentioned arm members, each of said sighting devices having a projecting portion adapted for insertion through the slot of said arm members, and means on said projecting portions for holding said sighting devices in adjusted position on said arm members.

5. A range finding, horizontal angle measuring and angle of site instrument comprising a trio of separable arm members pivotally connected together at one end, and adapted to be adjusted in angular relation to each other, means for holding said arm members in adjusted angular relation, a slot and an adjustable sighting device containing aiming marks provided on two of said arm members, a bolt and guide means provided on each of said sighting devices, said bolt adapted to project through the slot of said last mentioned arm members, and said guide means adapted to Work in said slots, means on said bolts for holding said sighting devices in adjusted position on said arm members, means on the other of said arm members defining the angular operative position of the first mentioned arm members, with respect thereto and with each other, and a mouth piece provided thereon, said mouth piece adapted to be held in the mouth of the observer for holding said first mentioned arm members a predetermined distance with respect to his eye.

6. A range finding, horizontal angle measuring and angle of site instrument, comprising a plurality of separable arm members pivotally connected together at one end, and adapted to be adjusted in angular relation to each other, means for holding said arm members in adjusted angular relation, one of said arm members adapted to be held in the mouth of the observer for holding the other of said arm members at a predetermined distance with respect to his eye, a sighting slide containing aiming marks slidably mounted on each of said last mentioned arm members, one of said last mentioned arm members bearing a plus and minus angle ofgsite' scale, a reflecting V surfacebearing, a reference at the zero ot the scale, and a weight on the free end of said-arm member, said last'mentioned arm member adaptj together at one-end, land iadaptedto be adjusted in angularrrelation'to each other,;separate means ed to be removed from its' pivotedconnection, and

pivotedfadjacent the inner end of said first mentioned arm 7 713A range finding, horizontal anglemeasuring and angle of site instrument-comprising:a-trio of separable arm members pivotally connected 'on two of said arm members'for holding said arm slot and an adjustable sighting device containing 7 I a members in adjusted angular position, with; re-

spect to each other and with the other arm mem'- her, means on Said last 'mentioned arm member defining the angular operative position of the first mentioned arm memberswith respect theretorand to each other, a longitudinally extending member on" the line of the zero of said 7 scale.

aiminglmarks providedfon eachof said first men I tioned arm members, a' bolt and guide means provided on each of said s'ighting devices; said bolt andfguide'means adapted to work in the slots of said arm members, a mouth piece including teeth stops provided on the freeend of the said other arm member, said mouth piece'adapted to 1 be held in the mouth'of the observer for holding the zfirst mentioned arm members a. predetermined distance from his veye, one of said first mentioned arm members bearing a 'plu'srand minus angle of site scale, a reflectingsurface bearing a reference at the zero of the scaleand V a weight on the free end of said arm member, said last mentioned arm member }adapted to be re- 'moved from its pivoted connection, and pivoted adjacentthe inner rend of the arm member containing said mouth piece on the line of the zero of saidrscale.

JOSEPH T. ZAKJ 2O 

